Triple-action drawing press



Nov. s, 1938. w ERNST 2,136,240

TRIPLE-ACTION DRAWING PRESS Filed April 16, 1956 INVENTOR 14m TEE 521x557.

ATTORN EY5.

Patented Nov. 8,

PATENT oi-Flee TRIPLE-ACTION DRAWING PRESS Walter Ernst, Mount Gilead, Ohio, assignor to The Hydraulic Press Corporation, Inc., Wile mington, Del., a corporation of Delaware Application. April 16, 1936, Serial No. 74,742

Iii-Claims. (Cl. 113-45) This invention relates to hydraulic presses, and in particular, to' drawing presses.

One object of this invention is to provide a triple-action drawing press having clamping and drawing devices, together with a movable support for the article being drawn, this support being arranged to provide a movable rest for the drawing device so as to prevent the latter from pushing its way through the article during the drawing operation.

Another object is to provide a drawing press having a supporting plunger which enters the drawing die and provides support for the end of the blank being drawn, the end of the plunger being preferably of a shape conforming to the shape of the bottom of the drawing die.

Another object is to provide a triple-action drawing press having a drawing plunger, a clampl ing plunger and a supporting plunger adaptedto support a portion of the article being drawn so as to prevent the drawing plunger from piercing the article, this supporting plunger being yieldable a suflicient amount to permit the drawing action to take place, yet not to such an extent that such piercing will occur.

Another object is to provide a drawing press of the type described immediately above, wherein the supporting plunger is received within a hydraulic cylinder connected to the main cylinder so that the pressure with which the supporting plunger will resist'the drawing operation is proportional to the pressure exerted by the .drawing plunger itself, this hydraulic cylinder preferably having a pressure relief valve associated therewith for regulating the. pressure at which the supporting plunger yields before the advance of the drawing plunger.

Another object is to provide a triple-action drawing press having a hydraulic main cylinder and ram for operating a drawing plunger, hy-

draulic clamping cylinders and rams for operating the clamping member, and a hydraulic supporting plunger for supporting a portion of the article being drawn during the drawing operation, the clamping plungers being hydraulically connected to the push-back side of the press so as to be operated by the fluid expelled therefrom during the advance of the. main plunger, the

clamping plungers preferably having a pressure relief valve associated therewith for releasing the clamping pressure when a predetermined, pres sure is being exerted.

In the drawing: v

The single figure shows a front elevation,

partly in section, of a triple-action. hydraulic drawing press and a hydraulic circuit in the diagrammatic form, according to this invention. Referring to the drawing in detail, the figure shows a hydraulic press having a base In, which is connected by uprights II to a top member l2. 5 The connection is maintained by means of strain rods l3, extending through the uprights II and having nuts l4 threaded upon the ends thereof.

Arranged to reciprocate vertically while guided on gibbed ways I5 is a platen l6, having guide 1 plates ll associated therewith. The platen I6 is also provided with an extension arm l8 adapted to operate a valve, in a manner subsequently to be described. The platen I6 is secured to one end of a main plunger IS, the head 20 of which 15 reciprocates within the main cylinder 2| associated with the top member l2 of the press.

Mounted in the main cylinder 2| is a surge valve 22 for admitting the pressure fluid into. the main cylinder during the gravitational descent 20 of the platen. The details of this surge valve 22 form no part of the present invention, and are disclosed in United States patent to Walter Ernst No.'1,892,568, issued December 27, 1932. The surge valve 22 is operated to be opened upon the 25 return stroke of the main plunger H by means of a pressure line 23 connected to the push-back line 24 of the press, which communicates with the port 25 opening into the push-back space beneath the main plunger head 20. The space 30 above the latter is served by means of the pressing line 26 communicating with the port 21. A surge tank 28 surrounds the main cylinder 2|, and provides fluid, such as oil, for the operation of the press, either through the surge valve 22 or 35 through the line 29 extending to the middle chamber 30 of. a make-up valve 3|, the left and rightend chambers 32 and 33 of which are connected to the pressing line 26 and push-back line 24,

respectively. 40

The make-up valve 3| is of a conventional type, whose details form no part of the present invention, and contains a valve member 3 having heads 35 joined by a fluted body portion 36. The purpose of the make-up valve 3| is to take care of 45 the need for fluid in any part of the circuit over that available fromthe' various cylinders themselves. This valve operates automatically to provide such fluid, in a manner well known to those skilled in the art. r .l 50 The opposite end chambers 32 and 33 are connected; respectively, to the pressing line 31 and the push-back. line 38 of a hydraulic pump 39. This pump is preferably of the. reversible variable deliverytype, with a servo-motor lll contain- 55 ing a piston (not shown) for moving the shiit ring of the pump to vary and reverse the delivery of the pump. The servo-motor 4 0 is controlled manually by a control valve 4| connected thereto by the lines Ma and 4|b and operated by the hand lever 42, and automatically by the line 48a running to the push-back line 38 of the pump 39. Fluid for operating the servo-motor 40 is provided through the lines 43 and 44 leading to the pressure and suction sides, respectively, of the low pressure pump 45, the line 44 being likewise connected to the line 28 leading from the make-up valve 3| to the surge tank 28. A pressure relief valve 48 by-passes the discharge of the pump 45 into the lines 44 and 29 when the valve 4| closes oii the line 43. The details of this control arrangement are disclosed in the patent to Walter Ernst No. 1,861,116, issued May 31, 1932.

Arranged within the base III of the press is a hydraulic cylinder 41, within which reciprocates the supporting plunger 48 of the press. The cylinder 41, near its upper end, is flanged to enter a bore 50 in the base in of the press, the upper portion of which is closed by a plate 5|, servingas a stop for shoulders 52 upon the supporting plunger 48 so as to limit the motion thereof. Leakage from the supporting plunger cylinder 41 is prevented by means of the gland 53, arranged to compress the packing 54 around the plunger. The upper part of the supporting plunger 48 passes through an aperture 55 in the plate iii, and through a corresponding aperture 56 in the drawing die 51, and enters the drawing die recess 58. The upper end 59 of the supporting plunger 48 is shaped to conform with the bottom of the drawing die recess 58, and serves to support the blank or work-piece 68 during the drawing operation. The supporting plunger cylinder 41 is connected by the line 6| containing the pressure relief valve 82, to the pressing line 26.

Arranged to enter the drawing die recess 58 and having a shape corresponding thereto is the drawing plunger 83, attached to and depending from the platen IS. The platen I6 is provided with clamping cylinder bores 64 forming clamping cylinders, within which reciprocate the clamping plungers 85. The latter are connected at their lower ends to the clamping member 88, which reciprocates vertically and which is suspended from the main platen l6 by means of the tie bolts 61 having their heads countersunk, as at 68, into the clamping member 68, and their opposite ends extending loosely through the bores 59 and held in position by the nuts 19 upon the upper ends thereof. Leakage around the clamping plungers 65 is prevented by means of the glands 1i arranged to compres'spackings 12.

Fluid is supplied to the clamping cylinders 64 from the push-back space beneath the main plungerhead 20 by means of the line 15, the opposite end of which terminates in the check valve 15. The line 11 is connected to the opposite side of the check valve 18 and joins the latter with the ports 18in the clamping cylinders 84. The

port 19 in one of the clamping cylinders 84 is connected to a pressure relief valve 80, and thence by the line 8| and flexible connection 82 to the line 83, entering the port 84 of the surge tank 28. The flexible connection 82, for convenience, is shown as a flexible pipe, but it will be understood that any other suitable arrangement for maintaining a connection between the clamping cylinders 84 and the surge tank 28 may be used. Similarly, the line 15 is shown as a passageway through the main plunger l9, but it-is of connection may be used. For example, instead of the flexible connection 82 and the drilled passage 15, tubular telescoping plungers or pivotally connected devices might be used to transmit the fluid during the motion of the platen. The lower end of the drawing plunger 53 passes through an aperture 85 in the clamping member 66, and likewise through an aperture 88 in a contact member 81 secured to the clamping member 88.

Mounted upon the side of the press is a valve 99, of any suitable type, and arranged to be op erated by a valve rod 9| supported at its upper end by the projection 92, upon the top member 12 of the press. Mounted upon the valve rod 9| and adjustable therealong is a collar 93, below which is a spring-urged cushion 94 for receiving the impact of the platen arm |8 as the platen moves upwardly. When the platen arm |8 engages the spring cushion 94 and moves the valve rod 9! upwardly, the valve 98 is opened and permits fluid to pass from the push-back line 38 of the pump 39, through the line 95, the valve 99, the line 88 and the check valve 91 into the supporting plunger cylinder 41. In this manner the opening of the valve 98 serves to admit pressure fluid tothe supporting plunger cylinder 41 so as to cause the supporting plunger 48 to be actuated Operation In starting the operation of the press to perform a pressing stroke, the main plunger i9 is allowed to descend by gravity and the pump 39 is started in operation. As the main plunger l9 descends, the suction created in the main cylinder 2|, above the head 28, draws in fluid from the surge tank 28 through the surge valve 22, thereby speeding the descent of the platen it over the speed which would occur in the event that the pump 39 alone was operating.

The platen l6 and the clamping member 68 continue to descend until the contact member 81 engages the blank or work-piece 80. The drawing plunger 83, however, continues to descend, and as .it encounters resistance in drawing the work, a pressure is built up in the main cylinder 2% by the operation of the pump 4|; By reason of the motion of the clamping cylinders 64 relatively to the now stationary clamping plungers 85, pressure is built up within the latter, and prevented from escaping by the closing of the check valve 18. The pressure thus developed by intensiflcation within the clamping plunger cylinders 65 causes the clamping plungers 65 to grip the work-piece with a pressure which is limited by the setting of the pressure relief valve 88. Accordingly, the work-piece 68 will be clamped with a constant pressure throughout the drawvalve 88 and the lines 8|, 82 and 83 into the surge tank 28.

When the drawing plunger 83 has descended to a point where it engages the bottom of the blank or work-piece 60, it forces the blank against the end 59 of the supporting plunger 48. This action builds up a pressure inside the into the main cylinder 2| by way of the pressing line 26. Accordingly, the harder the draw the tighter is the supporting force opposing the draw.

, 24, into the push-backspace beneath the main plunger head20, and lifting the main plunger mence.

blank, the other side being supported yieldingly bythe supporting plunger ll.

When the drawing plunger 83 reaches the-bottom of its stroke and the work-piece is fully formed from the blank '00, the pump 39 is reversed and the push-back pressure is discharged from the connection 49 into the line 38, through the. make-up valve 3i and the push-back line it.- This push-back pressure'passes downwardly through the'line 15, the check valve 16 and the; .line 11 into the clamping cylinders N, causing the clamping pressure to beexerted by the clamp.- ing 'plungers 85 on the blank while the'drawingv plunger 83 is-belng withdrawn, In this-manner i the work-piece is'stripped oi! the drawing plunger. After the drawing plunger 83 is drawn clear oi the work-piece it will raise the clamping member and contact member'll by means of the er in said cylinder having forward and return tie'bolts 61.] As the platen l6 continues to 'rise it. engages the spring cushion 84 and collar, so-

that the valve rod 9i rises. This opens the valve ill and allows pressure fluid toenter the supporting plunger cylinder 41, causing the support-- ing plunger 48 to act as a "knock-out plunger and expel the work-piece.

It will .be understood that the work-piece or blank 60 may be either a ilat plate or a concaved member, depending upon whether the drawing .operation being carried out is the first or succeeding drawing operation. For showing the general cas'e, the work-piece or blank 60 is illustrated in the drawing asconsistlng oi. a piece upon which one drawing operation has been made and a second drawing operation'isabout to com- It will be understood that separate push-back cylinders may-be used in place or a double-actingmain' plunger for returning the platen to itsinitial position. In such. case the connections I push-back means tor saidmain plunger, a platen attached to said main plunger, a clamping cylin- -der'and plunger assembly attached to said platen now made with the push-back side of the doubleacting main plunger or with thepush-back side oi the pump 39 wouldlbe 'made with the pushback cylinders or the lines leading thereto.

'It' will be understood that I-.desire to comprehend within this invention such modifications as -come withinthe scope of the'claims and the-invention. Having thus fully described my invention, what I claim as new and desire to secure by LettersP'atent, ist. 1. In combination, operated thereby, a forming V plunger connected thereto. a clamping plunger associated with said platen and operated by the motion thereof, a coope'rative'shaping die,'and a supporting plunger arranged to engage the workpiece and oppose the motion of said forming plunger, means for hydraulically connecting said supporting plunger with said main plunger; whereby to oppose the motion of said forming plunger by a torce proportional to the force exerted by said main plunger. I

, 2. 'In combination, a main plunger, hydraulic means for operating said main plunger, a platen operated'thereby, a forming plunger connected thereto, a cooperative shaping die, a supporting plunger device arranged to engage the work-- piece and oppose the motion of said forming,

a main plunger, a" platen plunger, valve means arranged to be operatedto supply pressure fluid to said supporting plunger device for expelling the work-piece in response to the arrival oi. said platen at a predetermined point during the return stroke thereof, and means hydraulically interconnecting said main plunger and said supporting plunger, whereby to causesaid supporting plunger to offer an opposing-force proportional to the pressure ex- 'erted by said main plunger.

3., In combination, a main plunger, a platen operated thereby, a forming plunger connected thereto, -a clamping plunger arranged on said platen to be operated by the motion'thereoi, a

cooperative shaping die, a supporting plunger arranged to engage the work-piece and oppose to'said supporting plungerfor expelling the workpiece in response to the arrival of said platen ata predetermined point'during the return stroke thereof, and means hydraulically interconnecting said main plungerand ,said supporting plunger. 4. In combination, a 1press frame having a bed, main cylinder, a double-acting main plungconnecting said main plunger with said supporting plunger, and pressure-responsive releasemeans iorreleasing pressure fluid from. said clamping plunger at, a predetermined pressure.

5. In comblnatioma' double-acting main plung- -er, hydraulic fluid-conducting means passing through said main plunger, a platen attached to the motion of said forming plunger, valve means arranged. to be operated to supply pressure fluid said main plunger, a clampingcylinder and plunger assemblyattached to said platen and connected to said fluid-conducting means, a fluid container, and means for maintaining a hy-' .draulic connection between said clamping assembly "and said fluid containers during the motion of said platen. 1

6. In combination, a main plunger, hydraulic and movable therewith, means for maintaining a hydraulic connection between said clamping assembly and said push-back means during the motion of said platemand a supporting plunger hydraulically connected to-.sai d main plunger and operated by pressure vfluid therefrom to oppose the motion thereoi'. v

'7. Incombination, a pressing plunger, a platen operated thereby, a clamping cylinder insaid platen,a clamping plunger in said cylinder,

means for supplying fluid to said clamping cylinder, and means responsive to the pressure built up in the clamping cylinder by the motion of said clamping cylinder relatively to said clamping platen, a clamping plunger in said cylinder, means for supplying fluid to said clamping cylinder,

means responsive to the pressure built up in the clamping cylinder by the motion of said clamp- 75 forming plunger connected-thereto, a clamping cylinder and plunger carried by said platen and movable relatively to one another to generate pressure in response to the motion of said platen to clamp the work-piece during the forming operation, a cooperative shaping die, pressure release means associated with said clamping plunger'to release fluid therefrom in response to the attainment of a predetermined clamping pressure whereby to clamp the work-piece with a predetermined force at a predetermined pressure, and fluid-conducting means connecting said clamping cylinder with said main cylinder for conducting to said clamping cylinder a portion of the fluid displaced from said main cylinder by the motion of said main plunger.

10. In combination, a main cylinder, a main plunger therein, a platen operated thereby, a forming plunger connected thereto, a clamping plunger member and a fluid-containing clamping cylinder member arranged to clamp the workpiece during the forming operation, a cooperative shaping die, one of said members being mounted on said platen and the other member being adapted to engage the work-piece, said members being movable relatively to one another to generate pressure for clamping the work-piece in response to the motion of said platen, a pressure release device associated with said clamping cylinder member whereby to clamp the workpiece with a predetermined pressure and to expel the fluid from said clamping cylinder member above said predeterminedpressure, and fluidconducting means connecting said clamping cylinder member with said-main cylinder for concylinder and hydraulically connecting said main 1 cylinder to said clamping cylinders whereby to supply to said clamping cylinders a portion of the fluid discharged from said main cylinder through said main plunger passageway as a result of the motion of said main plunger, clamping plungers j in said clamping cylinders, and a clamping element attached to said clamping plungers.

12. In combination, a main plunger, hydraulic means for operating said main plunger, a platen operated thereby, a forming plunger connected thereto, a hollow cooperative shaping die adapted to receive said forming plunger, a supporting plunger device arranged to engage the workpiece and oppose the motion of said forming plunger, said supporting plunger device being disposed within said hollow cooperative shaping die and having the end thereof configured coextensive with the adjacent surface of said cooperative shaping die, and means hydraulically interconnecting said main plunger and said supporting plunger, whereby to cause said supporting plunger to offer an opposing force proportional to the pressure exerted by said main plunger.

13. In combination, a press frame having a bed, a platen movable in said frame, hydraulic plunger-advancing and retracting means con-- nected to said platen for advancing and retracting said platen respectively, a clamping plunger hydraulically connected to said plunger-retracting means, a supporting plunger arranged to oppose the motion of said main plunger, means hydraulically interconnecting said main plunger with said supporting plunger, and pressure-responsive means for releasing pressure fluid from said clamping plunger at a predetermined pressure.

WALTER ERNST. 

